RecruitingBehavioural interventionHIT-Stroke Trial 2People who had a stroke at least 6 months prior and who still have difficulty with walking will each be randomly assigned to receive either moderate or vigorous intensity walking exercise. Both protocols will be performed individually with a physical therapist for 45 minutes, 3x/week for 12 weeks. Measures including walking function will be assessed at baseline (PRE), after 4, 8 and 12 weeks of training (12WK) and at 3-month follow up (3moPOST), by raters who are unaware of the participant randomization.